[60195]

I think what you are asking about is measuring the oil before pouring it in.

If that is the case, you are not measuring the oil in the fork. You are measuring the oil in the cup.

Not all of the old oil drains out of the tubes. When the new oil is measured, like in a measuring cup, not all of it pours. It sort of sticks to the cup. Harley even has its own tool for doing this. Sort of looks like this one:

Motion Pro Fork Oil Tool

Besides precision, the root differences between the two techniques is one is measuring the oil in a cup the other is measuring the oil in the tube. The difference to some might not be an issue.

 

[60195]

It will not make a difference if the front wheel is hanging or on the ground.

No, I did not mean anything about injecting oil through the drain holes. Whichever way you use, the new oil is still going into the top of the tubes.

What I was reffering to is how much oil is going into the tubes. You can premeasure and pour it, and that will get you close, but leaves allot of room for variation. The other way involves putting in more oil than is needed. And then using a suction tool that you can set the depth on to suck the oil down to a set height. This way will ensure the oil is at the correct height and that both tubes have the same amount of oil (and air above the oil).

A simple google search on fork oil tool will show many examples of the tool I am refering to. It goes into the hole in the top of the tube. Set the height on the tool, suck and the oil level will be set. This method provides very repeatable results.

 

[60195]

This job might take a half hour to an hour. On a table lift would be easiest. The key is to get the oil height correct. Most shop manuals will show two procedures.

The easy way is to simply drain and replace with a pre-measured amount of oil.

A more accurate way is to measure the oil level from the top of the tube. There are some inexpensive tools available to do this. Think large syringe, hose a rigid tube.

You could buy the fluid from the dealer, but there are better fluids available. RedLine and BellRay come to mind. Just be sure and match the oil weight to your application.